1. Field of the Invention
The present invention relates to a fuel delivery pipe with damper function adapted for use in an engine of the electronically controlled fuel injection type and a manufacturing method of the same.
2. Discussion of the Prior Art
Disclosed in Japanese Patent Publication No. 4230100 is a conventional fuel delivery pipe of this kind which is constructed of lower and upper cases integrally jointed by brazing, the lower case being provided at its bottom with a plurality of injection sockets spaced in a longitudinal direction for connection with fuel injection valves, and the upper case being in the form of a double walled structure the interior of which is subdivided into air chambers by means of a box-shaped wall panel in an air-tight manner. In the fuel delivery pipe, the air trapped in the air chambers is expanded and contracted by heating and cooling of the brazed wall panel, resulting in deformation of the wall panel. This causes difference in damper function of pressure pulsations of each fuel delivery pipe. To solve the problem, an air hole is provided in the upper case for communication with the atmosphere and is closed by a cap member after brazing process of the lower and upper cases. In a fuel delivery pipe disclosed in Japanese Patent No. 3217775, a damper member in the form of a metallic pipe of flat-circular in cross-section sealed at its opposite ends to contain therein gas is assembled within a case body of the fuel delivery pipe. The damper member is brazed at its opposite ends to the case body and is sealed at its one end after brazed by means of a seal plug attached from the exterior of the case body.
As in the fuel delivery pipes described above, the cap member or the seal plug is needed to close the air chamber in communication with the atmosphere, the number of component parts increases, resulting in difficulty of reduction of the manufacturing cost. As the head of the cap member projects from the fuel delivery pipe, a space for mounting the delivery pipe increases. In addition, the capacity for absorbing fluctuation of fuel pressure is restricted by the wall panel provided in the upper case.